Method of coating collapsible tubes



Mal-ch 28, 1939.

METHOD COATING OOLLAPSIBLE TUBES Fi led Feb. 24, 1936 ATTORNEY;

R. H. WHITE 2,152,516

Patented Mar. 28, 1%39 2,152,516 rmrnon or coa'rmo comnrsmm TUBES Application February 24, 1936, Serial No. 65,202

lead or aluminum, or of various alloys of these metals, or of various composite metals such as tin coated lead. It is usual to manufacture such tubes by extrusion. The substances formingthe contents of these tubes vary widely in their chemlcal composition. Some of these substances are alkaline in reaction, some acid andothers contain various salts or solvents which deleteriously react with the inner surface of the tube, occasionally eating through the relatively thin walls thereof in one or more spots or areas and more often forming compounds therewith which either discolor the contents or are tome or semi-toxic when absorbed by the tube contents.

One of the objects of the presentinvention is to provide the inner surface of the said .tube with an adherent inner coating which is eflectivp in protecting the said surface from deleterious interaction and corrosion by the contents in the tube.

Another object of the present-invention is to provide a coating which is effective to accomplish the desired protective result irrespective of the nature of the tube contents. Still another object is to provide an improved collapsible tube.

Before further disclosing the present invention reference should be made to the accompanying drawing, whereinz' Fig. 1 is an elevational view partly broken away is an enlarged sectional view of the same.

In accordance with the above objects, I have found that the inner surfaces of the said tubes may be protected from deleterious interaction with the said tube contents by coating the said wall with an elastic. sheath or thinfilm of material such as cellulosic esters, natural or synthetic resins, varnish, Bakelite compounds and the like which contain a filler comprised substantially of a metal or a compound of the said metal or both which are relatively low in the electromotive series of elements as compared to the metal comprising the tube surface. A suitable filler for the purposes of the present invention is, for example, tin, tin oxide or mixtures of tin and tin oxide. Alternatively bismuth or antimony may be employed. Other materials metallic and non-metallic may be suitable for use as a filler material in special cases but tin and tin to illustrate the present invention; and Fig. 2

oxide appear to have the added advantage of forming relatively insoluble oxidized tin compounds upon attack by acid or alkali, the more common corrosive agents to be found in the tube contents, and to resist attack and complete com- 5 bination therewith to such an extent that the reaction proceeds slowly thereby lengthening the period of attack and consequently the life of the coating.

Preferably the elastic film coating or sheath 10 should evidence a relatively high resistance to solution or penetration by organic solvents present in many of the common materials packaged in such tubes. This resistance is characteristic of phenolic resin compounds, known in the trade 16 as Bakelite. This compound normally is sold as a clear liquid which upon exposure to the atmosphere loses a solvent by evaporation leaving behind the hardened phenolic resin film.

With the introduction, of tiller material into 20 this varnish it is necessary to iadd to the mixture a suitable proportion 'of a plasticizer such as sulfonated rubber, for example, to impart to the dried film a desired flexibility which should be at least sufiicient to prevent the said film from cracking and pulling away from the metal surface during handling prior to and after filling the tube.

Itis customary in the art to apply such coatlugs to metal surfaces by spraying, dipping or by brushing the same thereon. The particle size of the said filler materials therefore should be such as to permit the continuance of this practice.

As a specific embodiment of the present invention but not as a limitation of the same, the protective film or sheath on the inner walls of the said collapsible tubes may be comprised of phenollc resin solution containing from 2 to 2 pounds of tin ground to pass 200-300 mesh to approximately each gallon of said solution, to which I add sulfonated rubber solution approximately 4 fluid ounces. The normal solvent utilized with phenolic resin is mineral spirits, and I add Just enough additional solvent (approximately 112 fluid ounces) as will facilitate the application of the material to the metal surface. In place of sulfonated rubber I- may use China-wood oil to the same amount (4 fluid ounces).

I may employ tin oxide to replace tin in part or in wholein the above composition, in which event I substitute 2 parts tin oxide for each 2 parts of tin. My preferred composition for filler material comprises tin and tin oxide in the proportion of 2 parts tin to 2 parts tin oxide.

The above composition in relatively thin film coatings 2 upon the inner surface of collapsible tube is efiective in protecting the inner surfaces of collapsible tubes from corrosion by either acid or alkali and from deleterious contact with various salts and solvents normally present in the contents of such tubes. This protection extends over a relatively long period of time as compared to uncoated tubes, and is particularly effective when used as a protective coating over lead, tin-lead alloys or over tin coated lead sur-. faces; In the latter case, the tin is not uniformly distributed over the lead surface and frequently the lead is exposed at isolated points, or in streaks or over relatively wide areas. Occasionally also the tin surface layer is relatively thin and readily eaten through by corroding agents to expose the under lead surface to more rapid attack which quickly penetrates through to the exterior surface.

While I'have disclosed as a specific embodiment tin and tin oxide as filler materials, and have described the use of the same in combination with phenolic resin solutions containing sulfonated rubber as a plasticizer, it is apparent that many other filler materials, plastic film materials and plasticizer materials may be utilized in the practice of the present invention and all such are contemplated as may fall within the scope of the accompanying claims.

-Having broadly and specifically described the present invention and given one specific embodiment of the same, all modifications and adaptations of the same are contemplated as may fall within the scope of the following claims.

What I claim is: a

l. The method of protecting the inner surface of a collapsible metal tube from attack'by acid and alkali constituents of the tube contents, which comprises coating the said inner surface with a thin elastic film of lacquer material resistant to destruction by the tube contents and containing a member of the group consisting of tin and oxides thereof.

2. A collapsible metallic tube having its inner surface coated with a lacquer resistant to destruction by the tube contents containing acidic or alkaline constituents and a finely divided member of the group consisting of tin and tin oxides.

3. The article of claim 2 in which said lacquer material comprises phenolic resin.

4. The article of claim 2 in which said lacquer film comprises a resin resistant to attack by the tube contents.

'5. The article of claim 2 in which the finely dividedmaterlal is an oxide of tin.

,6. The article of claim 2 in which the finely divided material is a metallic tin.

7. A method of protecting the inner surface of a collapsible metal tube from attack by acidic or alkaline tube filling materials which comprises coating the said inner surface with a thin elastic film of lacquer material resistant to destruction by said acidic or alkaline constituents and containing finely divided tin.

8. A method of protecting the inner surface of a collapsible metal tube from attack by acidic or alkaline tube filling materials which comprises coating said inner surface with a thin elastic film of a phenolic resin lacquer containing finely divided tin. I

9. A method of protecting the inner surface of a collapsible metal tube from attack by acidic or alkaline tube filling materials which comprises coating said inner surface with a thin elastic film of a phenolic resin lacquer containing a member of the group consisting of tin and its oxides.

I RAYMOND H. WHITE. 

